Material for forming silica-base coated insulation film, process for producing the material, silica-base insulation film, semiconductor device, and process for producing the device

ABSTRACT

A material for forming silica-base coated insulation films used to form interlayer insulation films of multi-layer interconnection in VLSIs is provided. A material for forming a silica-base coated insulation film, obtained from (a) an alkoxysilane and/or a partially hydrolyzed product thereof, (b) a fluorine-containing alkoxysilane and/or (e) an alkylalkoxysilane, (c) an alkoxide of a metal other than Si and/or a derivative thereof and (d) an organic solvent. The material for forming silica-base coated insulation films according to the present invention has a storage stability and also enables thick-layer formation. Silica-base insulation films obtained are transparent and uniform films and are those in which no defects such as cracks or pinholes are seen, also having a superior oxygen plasma resistance.

TECHNICAL FIELD

This invention relates to a material for forming silica-base coatedinsulation films used to form, e.g., interlayer insulation films ofmulti-layer interconnections (wiring) in super VLSI, and relates to aprocess for its production and a silica-base insulation film. Moreparticularly, this invention relates to a material for formingsilica-base coated insulation films that enables thick-layer formationon various substrates such as semiconductor substrates and glass platesand also has a good oxygen plasma resistance, and relates to a processfor its production and a silica-base insulation film.

BACKGROUND ART

In recent years, VLSIs have been rapidly made higher in packagingdensity and more highly integrated, and there is a demand for moremulti-layered aluminum wiring and for decreasing minimum working linewidth as its wiring patterns are made finer. Accordingly, multi-layerwiring interlayer insulation films used in such LSIs are required to beformed by a smoothing technique which fills wiring gaps withoutvacancies and also makes their surfaces smooth.

As interlayer insulation films that are required to be made smooth,films (SOG films) formed by what is called the spin-on-glass method (SOGmethod) are conventionally employed in which a coating solution obtainedby hydrolyzing an alkoxysilane and an alkylalkoxysilane in an organicsolvent such as alcohol in the presence of water and a catalyst isapplied by spin coating, followed by heating to cause coatings to cure.In particular, organic SOG films are mainly used in which the side chainof an organic component (an alkyl group such as methyl) is bonded to thebackbone chain of a siloxane bond, i.e., an organic component (an alkylgroup such as methyl) is left in the film, which can prevent cracks fromoccurring and improve smoothing properties to enable thick-layerformation.

The SOG films have advantages such that they cause less volumeshrinkage, show a hydrophobicity and have a low dielectric constant.However, when dry etching is carried out using oxygen plasma during thecourse of the fabrication of an LSI in order to strip a photosensitiveresist used to form contact holes that connect aluminum wiring providedat the lower layer and upper layer of the insulation film, this oxygenplasma causes alkyl groups in the film to be released, thus causingcracks. Accordingly, the insulation film is basically formed not in asingle layer structure but in a three-layer structure so that theorganic SOG film is not laid bare to the surface at the time of oxygenplasma processing, i.e., (i) an SiO₂ film serving as a base for SOG filmcoating is formed by plasma-assisted CVD, (ii) the organic SOG film isformed thereon by coating and etchback-treated and (iii)another SiO₂film serving as an upper coat is formed by plasma-assisted CVD.

FIG. 1 illustrates an example of a process for producing a semiconductordevice by the use of such an organic SOG film.

In FIG. 1, reference numeral 11 denotes a semiconductor chip substrateon which circuit electronic components such as a transistor, a diode, aresistor and a capacitor that constitute an electronic circuit areformed; 12, a first aluminum wiring formed on the semiconductor chipsubstrate; 13, the SiO₂ film serving as a base for coating the organicSOG film, formed by plasma-assisted CVD; and 14, the organic SOG film[FIG. 1 (a)]. Etchback treatment is carried out to subject the wholesurface of the organic SOG film 14 to oxygen plasma processing to makethe plasma CVD SiO₂ film laid bare at the part corresponding to thealuminum wiring 12 [FIG. 1 (b)]. Over the entire surface having beensubjected to etchback treatment, another SiO₂ film 15 serving as anupper coat is formed by plasma-assisted CVD, and a stated etching resist16 is formed thereon [FIG. 1 (c)]. The plasma CVD SiO₂ film at the partcorresponding to the aluminum wiring 12, not covered with the etchingresist 16, is removed by etching to make the aluminum wiring 12 exposed,and the etching resist is removed [FIG. 1 (d)]. Then, a second aluminumwiring 17 connected with the first aluminum wiring 12 is formed [FIG. 1(e)]. Thus a semiconductor device is produced.

However, as the VLSIs are made higher in packaging density and morehighly integrated, the space between aluminum wirings becomes so finethat the formation of the plasma CVD SiO₂ film serving as a base for SOGcoating makes the fine space between aluminum wirings still finer in theconventional three-layer structure, and hence an SOG coating solutioncan be caused to flow into the aluminum wiring space only withdifficulty, resulting in a defective state of burying the organic SOGfilm. For this reason, with a decrease in minimum working line width,which decreases as the aluminum wiring becomes finer, it has becomedifficult to form the interlayer insulation film in the conventionalthree-layer structure. Accordingly, it is desirable to provide an SOGfilm having a good oxygen plasma resistance and enabling formation ofthe interlayer insulation film even in a single-layer structure.

In order to shorten the semiconductor device fabrication process, aimingat a cost reduction, there is a demand for non-etchback type SOG filmsthat necessitate no etchback treatment. Accordingly, taking as a basisan inorganic SOG film (a film basically containing no organic component)having a good ashing resistance, it has been studied to add fine SiO₂particles, to use B-O and Mg-O bonds in combination or to introduce anSi-N skeleton, but no positive results have been forthcoming.

DISCLOSURE OF THE INVENTION

The present invention provides a material for forming silica-base coatedinsulation films that enables thick-film coating so as to improvesmoothing properties and also has a superior oxygen plasma resistance,and provides a process for its production and a silica-base insulationfilm.

The first invention of the present application is a material for formingsilica-base coated insulation films which is obtained from (a) analkoxysilane and/or a partially hydrolyzed product thereof, (b) afluorine-containing alkoxysilane, (c) an alkoxide of a metal other thanSi and/or a derivative thereof and (d) an organic solvent; and a processfor its production.

The second invention of the present application is a material forforming silica-base coated insulation films which is obtained from (a)an alkoxysilane and/or a partially hydrolyzed product thereof, (e) analkylalkoxysilane, (c) an alkoxide of a metal other than Si and/or aderivative thereof and (d) an organic solvent; and a process for itsproduction.

The third invention of the present application is a material for formingsilica-base coated insulation films which is obtained from (a) analkoxysilane and/or a partially hydrolyzed product thereof, (b) afluorine-containing alkoxysilane, (f) water and a catalyst and (d) anorganic solvent; and a process for its production.

The fourth invention of the present application is a process forproducing a material for forming silica-base coated insulation filmswhich is obtained from (a) an alkoxysilane, (e) an alkylalkoxysilaneand/or (b) a fluorine-containing alkoxysilane, (c) an alkoxide of ametal other than Si and/or a derivative thereof, (d) an organic solventand (f) water and a catalyst; the process comprising mixing thealkylalkoxysilane and/or the fluorine-containing alkoxysilane, the waterand the catalyst in an organic solvent, thereafter adding the alkoxideof a metal other than Si and/or the derivative thereof, further mixingthe alkoxysilane, and thereafter adding the water and the catalyst.

The fifth invention of the present application is a material for formingsilica-base coated insulation films which is obtained from (e) analkylalkoxysilane and/or (b) a fluorine-containing alkoxysilane, (c) analkoxide of a metal other than Si and/or a derivative thereof, (d) anorganic solvent and (f) water and a catalyst; and a process for itsproduction.

The sixth invention of the present application is a material for formingsilica-base coated insulation films which is obtained from (a) analkoxysilane and a partially hydrolyzed product thereof, (e) analkylalkoxysilane and/or (b) a fluorine-containing alkoxysilane, (c) analkoxide of a metal other than Si and/or a derivative thereof, (d) anorganic solvent and (g) a photo-acid-generator; and a process for itsproduction.

The first invention of the present application will be described below.

As the component-(a) alkoxysilane, we can enumerate a monomer or anoligomer of tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane,tetrabutoxysilane etc., which may each be used alone or in combinationof two or more kinds.

The partially hydrolyzed product of the alkoxysilane can be obtained byallowing a monomer or an oligomer of each alkoxysilane to react in anorganic solvent after addition of water and a catalyst such as anorganic acid, at a temperature not higher than the boiling point of theorganic solvent for a stated time.

As the catalyst, an acid or an alkali may be used as a catalyst forhydrolysis. The acid may include inorganic acids such as hydrochloricacid, nitric acid, sulfuric acid, phosphoric acid, boric acid andcarbonic acid, organic acids such as formic acid, acetic acid, propionicacid, butyric acid, lactic acid, malic acid, tartaric acid, citric acid,oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid,fumaric acid, maleic acid and oleic acid, and acid anhydrides orderivatives of these. The alkali may include sodium hydroxide, potassiumhydroxide, lithium hydroxide, ammonia, methylamine, ethylamine andethanolamine.

The water may be added in an amount ranging from 2 mols to 4 mols permol of the alkoxysilane. If added in an amount less than 2 mols, thealkoxysilane may be insufficiently hydrolyzed to make it difficult toform coatings at the time of coating. If added in an amount more than 4mols, the hydrolysis may take place abruptly and tend to cause coatingsolutions to gel. The catalyst may preferably be added in an amount offrom 0.1 part by weight to 5 parts by weight based on 100 parts byweight of the alkoxysilane. If it is added in an amount less than 0.1part by weight, the alkoxysilane may be insufficiently hydrolyzed tomake it difficult to form coatings at the time of coating. If added inan amount more than 5 parts by weight, the hydrolysis may take placeabruptly and tend to cause coating solutions to gel. There are noparticular limitations on the reaction temperature at the time ofhydrolysis. The temperature may preferably be not higher than theboiling point of the organic solvent used, and may particularlypreferably be 5° C. to 70° C. in order to control the molecular weightof the resultant hydrolyzed product. There are no particular limitationson the reaction time at the time of hydrolysis, and the reaction may becompleted at the time the product reaches a stated molecular weight.There are no particular limitations on how to measure the molecularweight here. A method employing liquid chromatography is simple andpreferred.

The component-(b) fluorine-containing alkoxysilane refers to analkoxysilane, an alkylalkoxysilane to the Si of which a fluorine atom isbonded, an alkylalkoxysilane at least part of alkyl groups of which hasbeen fluorinated, etc. each of which including a fluorine-containingalkylalkoxysilane. Specifically, we can enumeratefluorotrimethoxysilane, fluorotriethoxysilane,trifluoromethyltrimethoxysilane, trifluoromethyltriethoxysilane,trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane,tridecafluorooctyltrimethoxysilane, tridecafluorooctyltriethoxysilane,heptadecafluorodecyltrimethoxysilane,heptadecafluorodecyltriethoxysilane, fluoromethyldimethoxysilane,fluoromethyidiethoxysilane, trifluoromethylmethyidimethoxysilane,trifluoromethylmethyidiethoxysilane,trifluoropropylmethyldimethoxysilane,trifluoropropylmethyIdiethoxysilane,tridecafluorooctylmethyldimethoxysilane,tridecafluorooctylmethyldiethoxysilane,heptadecafluorodecylmethyldimethoxysilane,heptadecafluorodecylmethyidiethoxysilane, and so on. These may each beused alone or in combination of two or more kinds. As the component-(c)alkoxide of a metal other than Si, we can enumerate methoxide, ethoxid,propoxide, butoxide and the like of a metal such as Li, Na, Cu, Mg, Ca,Sr, Ba, Zn, B, Al, Ga, In, Y, Ge, Sn, Pb, Ti, Zr, P, Sb, V, Ta, Nb, orW. The derivative thereof are acetylacetonate derivatives of these etc.Any of these may each be used alone or in combination of two or morekinds. In particular, it is preferable to use an alkoxide of Al, Ti orZr or an acetylacetonate derivative thereof, which is especially readilyavailable as a commercial product, inexpensive and easy to handle.

As the component-(d) organic solvent, we can enumerate monohydricalcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol,and ethers or esters thereof, polyhydric alcohols such as glycerin andethylene glycol, and ethers or esters thereof, and ketones such asacetone, methyl ethyl ketone, methyl isobutyl ketone and acetyl acetone.These may each be used alone or in combination of two or more kinds.

The material for forming silica-base coated insulation films which isobtained from these four components (a), (b), (c) and (d) is produced bymixing the alkoxysilane and the fluorine-containing alkoxysilane in theorganic solvent, thereafter adding the alkoxide of a metal other than Siand/or the derivative thereof, and making the product have a highmolecular weight at room temperature or with heating. Here, in order tomore quickly make the product have a high molecular weight, water and anorganic acid may be added. The material may also be produced by addingthe water and the organic acid to the alkoxysilane in the organicsolvent to previously synthesize a partially hydrolyzed product thereof,and mixing in this product the fluorine-containing alkoxysilane,followed by addition of the alkoxide of a metal other than Si and/or thederivative thereof, to proceed with the reaction.

Here, the component (a) and the component (b) may preferably be used inan amount ranging from 1 part by weight to 40 parts by weight in total,based on 100 parts by weight of the organic solvent (d). If thecomponents (a) and (b) are in an amount less than 1 part by weight intotal, coatings may be formed only with difficulty at the time ofcoating. If they are in an amount more than 40 parts by weight, uniformfilms may be obtained only with difficulty. The component (b) maypreferably be added in an amount of from 0.1 mol to 10 mols per mol ofthe component (a). If the component (b) is added in an amount less than0.1 mol, cracks tend to occur at the time of heat-curing after coating.If it is added in an amount more than 10 mols, uniform films may beobtained only with difficulty. The component (c) may preferably be addedin an amount of from 0.01 mol to 0.5 mol per mol of the total of thecomponents (a) and (b). If the component (c) is added in an amount lessthan 0.01 mol, the product can be made to have a high molecular weightonly with difficulty. If added in an amount more than 0.5 mol, theproduct may abruptly come to have a high molecular weight, and hencecoating solutions tend to gel.

There are no particular limitations on the reaction temperature when theproduct is made to have a high molecular weight. The temperature maypreferably be not higher than the boiling point of the organic solventused, and may particularly preferably be 5° C. to 70° C. in order tocontrol the molecular weight of the resultant hydrolyzed product. Thereare no particular limitations on the reaction time at the time ofhydrolysis, and the reaction may be completed at the time the productreaches a stated molecular weight. There are no particular limitationson how to measure the molecular weight here. A method employing liquidchromatography is simple and is preferred.

The second invention will be described below.

Of the components used in the second invention, (a) the alkoxysilaneand/or the partially hydrolyzed product thereof, (c) the alkoxide of ametal other than Si and/or the derivative thereof and (d) the organicsolvent are the same as those as described above.

As the component-(e) alkylalkoxysilane we can enumeratemethyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane,methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane,ethyltripropoxysilane, ethyltributoxysilane, propyltrimethoxysilane,propyltriethoxysilane, propyltripropoxysilane, propyltributoxysilane,phenyltrimethoxysilane, phenyltriethoxysilane, phenyltripropoxysilane,phenyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane,dimethyidipropoxysilane, dimethyldibutoxysilane, diethyldimethoxysilane,diethyidiethoxysilane, diethyidipropoxysilane, diethyldibutoxysilane,dipropyldimethoxysilane, dipropyldiethoxysilane,dipropyldipropoxysilane, dipropyldibutoxysilane,diphenyldimethoxysilane, diphenyldiethoxysilane,diphenyidipropoxysilane, diphenyldibutoxysilane,aminopropyltrimethoxysilane, aminopropyltriethoxysilane,aminopropylmethyldimethoxysilane, aminopropyidimethylmethoxysilane,3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane,3-glycidoxypropylmethyldimethoxysilane,3-glycidoxypropyldimethylmethoxysilane,3-methacryloxypropyltrimethoxysilane,3-methacryloxypropyltriethoxysilane,3-methacryloxypropylmethyldimethoxysilane,3-methacryloxypropyidimethylmethoxysilane, vinyltrimethoxysilane,vinyltriethoxysilane, vinylmethyldimethoxysilane,vinyidimethylmethoxysilane, etc. These may each be used alone or incombination of two or more kinds.

The material for forming silica-base coated insulation films which isobtained from these four components (a), (e), (c) and (d) is produced bymixing the alkoxysilane and the alkylalkoxysilane in the organicsolvent, thereafter adding the alkoxide of a metal other than Si and/orthe derivative thereof, and making the product have a high molecularweight at room temperature or with heating. Here, in order to morequickly make the product have a high molecular weight, water and/or acatalyst may be added. The material may also be produced by adding thewater and the catalyst to the alkoxysilane in the organic solvent topreviously synthesize a partially hydrolyzed product thereof, and mixingin this product the alkylalkoxysilane, followed by addition of thealkoxide of a metal other than Si and/or the derivative thereof, toproceed with the reaction.

Here, the component (a) and the component (e) may preferably be used inan amount ranging from 1 part by weight to 40 parts by weight in total,based on 100 parts by weight of the organic solvent (d). If thecomponents (a) and (e) are in an amount less than 1 part by weight intotal, coatings may be formed only with difficulty at the time ofcoating. If they are in an amount more than 40 parts by weight, uniformfilms may be obtained only with difficulty. The component (e) maypreferably be added in an amount of from 0.1 mol to 10 mols per mol ofthe component (a). If the component (e) is added in an amount less than0.1 mol, cracks tend to occur at the time of heat-curing after coating.If it is added in an amount more than 10 mols, uniform films may beobtained only with difficulty. The component (c) may preferably be addedin an amount ranging from 0.01 mol to 0.5 mol per mol of the total ofthe components (a) and (e). If the component (c) is added in an amountless than 0.01 mol, the product can be made to have a high molecularweight only with difficulty. If added in an amount more than 0.5 mol,the product may abruptly come to have a high molecular weight, and hencecoating solutions tend to gel.

There are no particular limitations on the reaction temperature when theproduct is made to have a high molecular weight. The temperature maypreferably be not higher than the boiling point of the organic solventused, and may particularly preferably be 5° C. to 70° C. in order tocontrol the molecular weight of the resultant hydrolyzed product. Thereare no particular limitations on the reaction time at the time ofhydrolysis, and the reaction may be completed at the time the productreaches a stated molecular weight. There are no particular limitationson how to measure the molecular weight here. A method employing liquidchromatography is simple and is preferred.

The third invention will be described below.

Of the components used in the third invention, (a) the alkoxysilaneand/or the partially hydrolyzed product thereof, (b) thefluorine-containing alkoxysilane and (d) the organic solvent are thesame as those previously described.

As the component-(f) catalyst, an acid or an alkali may be used. As theacid, we can enumerate inorganic acids such as hydrochloric acid, nitricacid, sulfuric acid, phosphoric acid, boric acid and carbonic acid,organic acids such as formic acid, acetic acid, propionic acid, butyricacid, lactic acid, malic acid, tartaric acid, citric acid, oxalic acid,malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid,maleic acid and oleic acid, and acid anhydrides or derivatives of these.The alkali may include sodium hydroxide, potassium hydroxide, lithiumhydroxide, ammonia, methylamine, ethylamine and ethanolamine.

The material for forming silica-base coated insulation films which isobtained from these four components (a), (b), (f) and (d) is produced bymixing the alkoxysilane and the fluorine-containing alkoxysilane in theorganic solvent, thereafter adding the water and the catalyst, andcarrying out the reaction at room temperature or with heating. Thematerial may also be produced by adding the water and the catalyst tothe alkoxysilane in the organic solvent to previously synthesize apartially hydrolyzed product thereof, and adding to this product thefluorine-containing alkoxysilane, followed by addition of the water andthe catalyst, to proceed with the reaction.

Here, the component (a) and the component (b) may preferably be used inan amount ranging from 1 part by weight to 40 parts by weight in total,based on 100 parts by weight of the organic solvent (d). If thecomponents (a) and (b) are in an amount less than 1 part by weight intotal, coatings may be formed only with difficulty at the time ofcoating. If they are in an amount more than 40 parts by weight, uniformfilms may be obtained only with difficulty. The component (b) maypreferably be added in an amount of from 0.1 mol to 10 mols per mol ofthe component (a). If the component (b) is added in an amount less than0.1 mol, cracks tend to occur at the time of heat-curing after coating.If it is added in an amount more than 10 mols, uniform films may beobtained only with difficulty. The water of component (f) may preferablybe added in an amount ranging from 2 mols to 4 mols per mol of the totalof the components (a) and (b). If the water is added in an amount lessthan 2 mols, the components (a) and (b) may be insufficiently hydrolyzedto make it difficult to form coatings at the time of coating. If addedin an amount more than 4 mols, the hydrolysis may abruptly take place totend to cause coating solutions to gel. The catalyst of component (f)may preferably be added in an amount of from 0.1 part by weight to 5parts by weight based on 100 parts by weight of the total of thecomponents (a) and (b). If it is added in an amount less than 0.1 partby weight, the components (a) and (b) may be insufficiently hydrolyzedto make it difficult to form coatings at the time of coating. If addedin an amount more than 5 parts by weight, the hydrolysis may abruptlytake place to tend to cause coating solutions to gel.

There are no particular limitations on the reaction temperature at thetime of hydrolysis. The temperature may preferably be not higher thanthe boiling point of the organic solvent used, and may particularlypreferably be 5° C. to 70° C. in order to control the molecular weightof the resultant hydrolyzed product. There are no particular limitationson the reaction time at the time of hydrolysis, and the reaction may becompleted at the time the product reaches a stated molecular weight.There are no particular limitations on how to measure the molecularweight here. A method employing liquid chromatography is simple and ispreferred.

The materials for forming silica-base coated insulation films accordingto the first, second and third invention as described above are coatedon substrates, and the coatings formed are dried to remove the organicsolvent, followed by heat-curing at 300° C. or above, so that thesilica-base insulation films can be formed. Here, the materials may becoated by a coating method including spin coating, spraying and dipcoating, without any particular limitations. There are no particularlimitations on drying temperature, which may preferably be in the rangeof from 100° C. to 300° C. in order to accelerate the evaporation of theorganic solvent. The heat-curing may be carried out at a temperature of300° C. or above without any particular limitations. Its upper limitdepends on the type of the substrates used. When, for example, thoseprovided with aluminum wiring as in LSIs are used, the temperature maypreferably be 500° C. or below. There are no particular limitations onheat-curing time, and the heating may be completed at the time thephysical properties of the films formed after curing have substantiallyreached equilibrium. There are no particular limitations on how to makejudgement on that time. Measurement of the surface hardness of films orthickness of films is simple and is preferred. There are no particularlimitations on atmospheres at the time of heat-curing. It is preferableto introduce an inert gas such as nitrogen or argon so that alkyl groupsin the component (b) or (e) may be released less during heating.

The fourth invention will be described below.

Of the components used in the fourth invention, (a) the alkoxysilane,(e) the alkylalkoxysilane and/or (b) the fluorine-containingalkoxysilane, (c) the alkoxide of a metal other than Si and/or thederivative thereof, (d) the organic solvent and (f) the water and thecatalyst are the same as those previously described.

The water may preferably be added in an amount less than 75% based on100% of the alkoxyl groups of the respective alkylalkoxysilane and/orfluorine-containing alkoxysilane. If it is added in an amount not lessthan 75%, the hydrolysis of the alkoxysilane, alkylalkoxysilane, and/orfluorine-containing alkoxysilane may take place abruptly and tend tocause coating solutions to gel or cloud. The catalyst may preferably beadded in an amount of from 0.1 part by weight to 5 parts by weight basedon 100 parts by weight of the alkoxysilane, alkylalkoxysilane, and/orfluorine-containing alkoxysilane. If it is added in an amount less than0.1 part by weight, the alkoxysilane, alkylalkoxysilane, and/orfluorine-containing alkoxysilane may be insufficiently hydrolyzed tomake it difficult to form coatings at the time of coating. If added inan amount more than 5 parts by weight, the hydrolysis may take placeabruptly and tend to cause coating solutions to gel. There are noparticular limitations on the reaction temperature at the time ofhydrolysis. The temperature may preferably be not higher than theboiling point of the organic solvent used, and may particularlypreferably be 5° C. to 70° C. in order to control the molecular weightof the resultant hydrolyzed product. There are no particular limitationson the reaction time at the time of hydrolysis, and the reaction may becompleted at the time the product reaches a stated molecular weight.There are no particular limitations on how to measure the molecularweight here. A method employing liquid chromatography is simple and ispreferred.

The material for forming silica-base coated insulation films which isobtained from (a) the alkoxysilane, (e) the alkylalkoxysilane and/or (b)the fluorine-containing alkoxysilane, (c) the alkoxide of a metal otherthan Si and/or the derivative thereof, (d) the organic solvent and (f)the water and the catalyst is produced in the following way: First, astated amount of the alkylalkoxysilane and/or the fluorine-containingalkoxysilane are dispersed in the organic solvent. In the dispersionobtained, the water and the catalyst are mixed, and the mixture isstirred for a while, followed by addition of the alkoxide of a metalother than Si and/or the derivative thereof. The mixture is furtherstirred for a while to proceed with the reaction, and thereafter thealkoxysilane is added and well mixed, followed by addition of the waterand/or the catalyst to cause the product to have a high molecular weightat room temperature or with heating.

Here, the component (a) and the components (e) and/or (b) may preferablybe used in an amount ranging from 1 part by weight to 40 parts by weightin total, based on 100 parts by weight of the organic solvent (d). Ifthe components (a) and the components (e) and/or (b) are in an amountless than 1 part by weight in total, coatings may be formed only withdifficulty at the time of coating. If they are in an amount more than 40parts by weight, uniform films may be obtained only with difficulty. Thecomponents (e) and/or (b) may preferably be added in an amount of from0.1 mol to 10 mols per mol of the component (a). If the components (e)and/or (b) is added in an amount less than 0.1 mol, cracks tend to occurat the time of heat-curing after coating. If it is added in an amountmore than 10 mols, uniform films may be obtained with difficulty. Thecomponent (c) may preferably be added in an amount ranging from 0.01 molto 1 mol per mol of the total of the components (a) and the components(e) and/or (b). If the component (c) is added in an amount less than0.01 mol, the product cannot be made to have a sufficiently highmolecular weight, and hence coatings may be formed only with difficultyat the time of coating. If added in an amount more than 1 mol, theproduct may abruptly come to have a high molecular weight, and hencecoating solutions tend to gel.

There are no particular limitations on the reaction temperature when theproduct is made to have a high molecular weight. The temperature maypreferably be not higher than the boiling point of the organic solventused, and may particularly preferably be 5° C. to 70° C. in order tocontrol the molecular weight of the resultant hydrolyzed product. Thereare no particular limitations on the reaction time at the time ofhydrolysis, and the reaction may be completed at the time the productreaches a stated molecular weight. There are no particular limitationson how to measure the molecular weight here. A method employing liquidchromatography is simple and is preferred.

The material for forming silica-base coated insulation films, thusproduced, is coated on substrates, and the coatings formed are dried toremove the organic solvent, followed by heat-curing at 300° C. or above,so that the silica-base insulation films can be formed. Here, thematerial may be coated by a coating method including spin coating,spraying and dip coating, without any particular limitations. There areno particular limitations on drying temperature, which may preferably bein the range of from 100° C. to 300° C. in order to accelerate theevaporation of the organic solvent. The heat-curing may be carried outat a temperature of 300° C. or above without any particular limitations.Its upper limit depends on the type of the substrates used. When, forexample, those provided with aluminum wiring as in LSls are used, thetemperature may preferably be 500° C. or below. There are no particularlimitations on heat-curing time, and the heating may be completed at thetime the physical properties of the films formed after curing havesubstantially reached equilibrium. There are no particular limitationson how to make judgement on that time. Measurement of the surfacehardness of films or thickness of films is simple and is preferred.There are no particular limitations on atmospheres at the time ofheat-curing. It is preferable to introduce an inert gas such as nitrogenor argon so that alkyl groups in the components (e) and/or (b) may bereleased less during heating.

The fifth invention will be described below.

Of the components used in the fifth invention, (e) the alkylalkoxysilaneand/or (b) the fluorine-containing alkoxysilane, (c) the alkoxide of ametal other than Si and/or the derivative thereof, (d) the organicsolvent and (f) the water and the catalyst are the same as thosepreviously described.

The water may preferably be added in an amount less than 75% based on100% of the alkoxyl groups of the respective alkylalkoxysilane and/orfluorine-containing alkoxysilane. If it is added in an amount not lessthan 75%, the hydrolysis of the alkylalkoxysilane and/orfluorine-containing alkoxysilane may take place abruptly and tend tocause coating solutions to gel or cloud. The catalyst may preferably beadded in an amount of from 0.1 part by weight to 5 parts by weight basedon 100 parts by weight of the alkylalkoxysilane and/orfluorine-containing alkoxysilane. If it is added in an amount less than0.1 part by weight, the alkylalkoxysilane and/or fluorine-containingalkoxysilane may be insufficiently hydrolyzed to make it impossible toform coatings at the time of coating. If added in an amount more than 5parts by weight, the hydrolysis may take place abruptly and tend tocause coating solutions to gel. There are no particular limitations onthe reaction temperature at the time of hydrolysis. The temperature maypreferably be not higher than the boiling point of the organic solventused, and may particularly preferably be 5° C. to 70° C. in order tocontrol the molecular weight of the resultant hydrolyzed product. Thereare no particular limitations on the reaction time at the time ofhydrolysis, and the reaction may be completed at the time the productreaches a stated molecular weight. There are no particular limitationson how to measure the molecular weight here. A method employing liquidchromatography is simple and is preferred.

The material for forming silica-base coated insulation films which isobtained from (e) the alkylalkoxysilane and/or (b) thefluorine-containing alkoxysilane, (c) the alkoxide of a metal other thanSi and/or the derivative thereof, (d) the organic solvent and (f) thewater and the catalyst is produced in the following way: First, a statedamount of the alkylalkoxysilane and/or the fluorine-containingalkoxysilane are dispersed in the organic solvent. In the dispersionobtained, the water and the catalyst are mixed, and the mixture isstirred for a while, followed by addition of the alkoxide of a metalother than Si and/or the derivative thereof to make the product have ahigh molecular weight at room temperature or with heating.

Here, the components (e) and/or (b) may preferably be used in an amountranging from 1 part by weight to 40 parts by weight in total, based on100 parts by weight of the organic solvent (d). If the components (e)and/or (b) are in an amount less than 1 part by weight in total,coatings may be formed only with difficulty at the time of coating. Ifthey are in an amount more than 40 parts by weight, uniform films may beobtained with difficulty. The component (c) may preferably be added inan amount ranging from 0.01 mol to 1 mol per mol of the total of thecomponents (e) and/or (b). If the component (c) is added in an amountless than 0.01 mol, the product cannot be made to have a sufficientlyhigh molecular weight, and hence coatings may be formed only withdifficulty at the time of coating. If added in an amount more than 1mol, the product may abruptly come to have a high molecular weight, andhence coating solutions tend to gel.

There are no particular limitations on the reaction temperature when theproduct is made to have a high molecular weight. The temperature maypreferably be not higher than the boiling point of the organic solventused, and may particularly preferably be 5° C. to 70° C. in order tocontrol the molecular weight of the resultant hydrolyzed product. Thereare no particular limitations on the reaction time at the time ofhydrolysis, and the reaction may be completed at the time the productreaches a stated molecular weight. There are no particular limitationson how to measure the molecular weight here. A method employing liquidchromatography is simple and is preferred.

The material for forming silica-base coated insulation films, thusproduced, is coated on substrates, and the coatings formed are dried toremove the organic solvent, followed by heat-curing at 300° C. or above,so that the silica-base insulation films can be formed. Here, thematerial may be coated by a coating method including spin coating,spraying and dip coating, without any particular limitations. There areno particular limitations on drying temperature, which may preferably bein the range of from 100° C. to 300° C. in order to accelerate theevaporation of the organic solvent. The heat-curing may be carried outat a temperature of 300° C. or above without any particular limitations.However, its upper limit depends on the type of the substrates used.When, for example, those provided with aluminum wiring as in LSIs areused, the temperature may preferably be 500° C. or below. There are noparticular limitations on heat-curing time, and the heating may becompleted at the time the physical properties of the films formed aftercuring have substantially reached equilibrium. There are no particularlimitations on how to make judgement on that time. Measurement of thesurface hardness of films or thickness of films is simple and ispreferred. There are no particular limitations on atmospheres at thetime of heat-curing. It is preferable to introduce an inert gas such asnitrogen or argon so that alkyl groups in the components (e) and/or (b)may be released less during heating.

The sixth invention of the present application is a material for formingsilica-base coated insulation films which is obtained from (a) analkoxysilane and/or a partially hydrolyzed product thereof, (e) analkylalkoxysilane and/or (b) a fluorine-containing alkoxysilane, (c) analkoxide of a metal other than Si and/or a derivative thereof, (d) anorganic solvent and (g) a photo-acid-generator; and a process for itsproduction.

Of the components used in the sixth invention, (a) the alkoxysilaneand/or the partially hydrolyzed product thereof, (e). thealkylalkoxysilane and/or (b) the fluorine-containing alkoxysilane, (c)the alkoxide of a metal other than Si and/or the derivative thereof and(d) the organic solvent are the same as those previously described.

As the component-(g) photo-acid-generator we can enumeratediphenyliodonium salts such as diphenyliodoniumtrifluoromethanesulfonate, bis(4-t-butylphenyl)iodonium salts such asbis(4-t-butylphenyl)iodonium hexafluoroantimonate, triphenylsulfoniumsalts such as triphenylsulfonium trifluomethanesulfonate, triazines suchas 2,4,6-tris(trichloromethyl)-1,3,5-triazine, and sulfonates such asbenzoin tosylate, etc. These may each be used alone or in combination oftwo or more kinds.

The material for forming silica-base coated insulation films which isobtained from these components (a), (e) and/or (b), (c), (d), and (g) isproduced by mixing the alkoxysilane and the alkylalkoxysilane and/or thefluorine-containing alkoxysilane in the organic solvent, thereafteradding the alkoxide of a metal other than Si and/or the derivativethereof, and causing the product to have a high molecular weight at roomtemperature or with heating, followed by addition of thephoto-acid-generator.

Here, in order to more quickly make the product have a high molecularweight, water and an organic acid may be added. The material may also beproduced by adding the water and the organic acid to the alkoxysilane inthe organic solvent to previously synthesize a partially hydrolyzedproduct thereof, and mixing in this product the alkylalkoxysilane and/orthe fluorine-containing alkoxysilane, followed by addition of thealkoxide of a metal other than Si and/or the derivative thereof.

Here, the component (a) and the components (e) and/or (b) may preferablybe used in an amount ranging from 1 part by weight to 40 parts by weightin total, based on 100 parts by weight of the organic solvent (d). Ifthe components (a) and the components (e) and/or (b) are in an amountless than 1 part by weight in total, coatings may be formed only withdifficulty at the time of coating. If they are in an amount more than 40parts by weight, uniform films may be obtained only with difficulty. Thecomponents (e) and/or (b) may preferably be added in an amount of from0.1 mol to 10 mols per mol of the component (a). If the components (e)and/or (b) is added in an amount less than 0.1 mol, cracks tend to occurat the time of heat-curing after coating. If it is added in an amountmore than 10 mols, uniform films may be obtained only with difficulty.The component (c) may preferably be added in an amount ranging from 0.01mol to 0.5 mol per mol of the total of the components (a) and thecomponents (e) and/or (b). If the component (c) is added in an amountless than 0.01 mol, the product cannot be made to have a sufficientlyhigh molecular weight, and hence coatings may be formed only withdifficulty at the time of coating. If added in an amount more than 0.5mol, the product may abruptly come to have a high molecular weight, andhence coating solutions tend to gel. The component (g) may preferably beadded in an amount not less than 0.1 mol % based on the total weight ofthe components (a) and the components (e) and/or (b). If the component(g) is added in an amount less than 0.1 mol %, it may generate acid in asmall amount at the time of exposure to light, resulting in aninsufficient pattern formation.

There are no particular limitations on the reaction temperature when theproduct is made to have a high molecular weight. The temperature maypreferably be not higher than the boiling point of the organic solventused, and may particularly preferably be 5° C. to 70° C. in order tocontrol the molecular weight of the resultant hydrolyzed product. Thereare no particular limitations on the reaction time at the time ofhydrolysis, and the reaction may be completed at the time the productreaches a stated molecular weight. There are no particular limitationson how to measure the molecular weight here. A method employing liquidchromatography is simple and is preferred.

The material for forming silica-base coated insulation films, thusproduced, is coated on substrates, and the coatings formed are dried toremove the organic solvent, followed by exposure to light and thereafterheat-curing, and the heat-cured product obtained is developed, so thatpatterned silica-base thin films can be formed. Here, the material maybe coated by a coating method including spin coating, spraying and dipcoating, without any particular limitations. There are no particularlimitations on drying temperature, which may preferably be in the rangeof 40° C. or above in order to accelerate the evaporation of the organicsolvent. The coatings formed may be exposed to light by a method such ascontact exposure, proximity exposure, projection exposure or reductionprojection exposure, without any particular limitations. The heat-curingafter the exposure may be carried out at a temperature of 80° C. orabove without any particular limitations. Its upper limit depends on thetype of the substrates used. When, for example, plastic substrates madeof polycarbonate etc. are used, the temperature may preferably be 100°C. or below. There are no particular limitations on heat-curing time,and the heating may be completed at the time the physical properties ofthe films formed after curing have substantially reached equilibrium.There are no particular limitations on how to make judgement on thattime. Measurement of the surface hardness of films or thickness of filmsis simple and is preferred. There are no particular limitations onatmospheres at the time of heat-curing. It is preferable to introduce aninert gas such as nitrogen or argon so that alkyl groups in thecomponents (e) and/or (b) may be released less during heating. As amethod for the development, it may include the alkali development, whichmakes use of an aqueous ammonium hydroxide type solution, the solventdevelopment, which makes use of organic solvents such as alcohols andketones, without any particular limitations, which are those used inconventional resist materials. In order to enhance the hardness of thinfilms obtained, the films may be heated again after the development.

FIG. 2 illustrates an example of a process for producing a semiconductordevice by the use of the material for forming silica-base coatedinsulation films according to the present invention.

In FIG. 2, reference numeral 21 denotes a semiconductor chip substrateon which circuit electronic components such as a transistor, a diode, aresistor and a capacitor that constitute an electronic circuit areformed; 22, a first wiring such as a first aluminum wiring formed on thesemiconductor chip substrate; an SiO₂ film formed by plasma-assistedCVD; and 24, an insulation film formed using the material for formingsilica-base coated insulation films according to the present invention[FIG. 2 (a)]. Over the entire surface of the insulation film 24 of thepresent invention, another SiO₂ film 25 is formed by plasma-assistedCVD, and a stated etching resist 26 is formed thereon [FIG. 2 (b)].Etching treatment is made by dry etching using oxygen plasma etc. toremove the insulation film 24 at the part not covered with the etchingresist 26, to thereby expose the first wiring 22 uncovered, and theetching resist is removed [FIG. 2 (c)]. Then, a second wiring 27 such asa second aluminum wiring connected with the first wiring 22 is formed[FIG. 2 (d)]. Thus a semiconductor device is produced.

The SiO₂ film 25 formed by plasma-assisted CVD over the entire surfaceof the insulation film 24 of the present invention may be omitted.

The SiO₂ film 23 formed by plasma-assisted CVD on the surfaces of thesemiconductor chip substrate 21 and first wiring 22 may also be omitted.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates, in cross-section, a process for producing asemiconductor device by the use of a conventional organic SOG film.

FIG. 2 illustrates, in cross-section, a process for producing asemiconductor device by the use of the insulation film of the presentinvention.

FIG. 3 illustrates, in a graph, the result of the measurement on surfaceroughness of the patterned silica-base thin film formed in example 19.

BEST MODES FOR WORKING THE INVENTION EXAMPLE 1

In 345 g (7.5 mols) of ethyl alcohol, 152 g (1 mol) oftetramethoxysilane and 54.5 g (0.25 mol) oftrifluoropropyltrimethoxysilane were added. These were well mixed, andthereafter a solution prepared by dissolving 42.5 g (0.125 mol) oftetrabutoxytitanium in 230 g (5 mols) of ethyl alcohol was added whilecontinuing to stir the mixture. While further continuing to stir themixture, the reaction was allowed to proceed for 24 hours to produce amaterial for forming silica-base coated insulation films. With respectto this insulation film forming material, its molecular weightdistribution was measured using tetrahydrofuran as an eluting solutionand using an HPLC (high-speed liquid chromatography) apparatus (Model6000, manufactured by Hitachi Ltd.). From the results of measurement,number average molecular weight in terms of polystyrene was calculated(columns used: available from Hitachi Chemical Co., Ltd.; trade name:GELPACK GL-R420; flow rate: 1.75 ml/min.). As a result, it was fond tobe about 2,640. This insulation film forming material did not gel at alleven after being left to stand at room temperature for a month.

Using 1.5 ml of this material for forming silica-base coated insulationfilms, a silicon wafer having been mirror-polished on one side wascoated with this material on its surface by means of a spin coater at1,500 rpm for 20 seconds, followed by drying for 10 minutes with a 150°C. dryer to remove the solvent. Subsequently, using a tubular bakingfurnace and in an atmosphere of nitrogen, the coating formed was heatedat 400° C. for 30 minutes to cure, to thereby obtain a transparent anduniform silica-base insulation film. Using an automatic elipsometer(manufactured by Mizoshiri Kogaku Kogyosho), the thickness of thisinsulation film was measured to find that it was 537 nm. Also, using anoptical microscope, the surface of this insulation film was observed,where none of defects such as cracks and pinholes were seen.

This silica-base insulation film was subjected to oxygen plasmatreatment using a barrel type isotropic plasma etching apparatus andunder conditions of oxygen:1 Torr, output: 400 W, time: 20 minutes.Thereafter, the thickness of the film thus treated was measured toreveal that it was 521 nm, and it was seen that its layer thicknessbecame smaller by only about 3% even when exposed to oxygen plasma.Also, using an optical microscope, the surface of this insulation filmwas observed, and no defects such as cracks or pinholes were seen.

An IR spectrum of this insulation film was also measured. As a result,an absorption peak ascribable to the alkyl group (trifluoropropyl group)was also seen after the oxygen plasma treatment, and the film was foundto have a good oxygen plasma resistance.

EXAMPLE 2

In 345 g (7.5 mols) of ethyl alcohol, 152 g (1 mol) oftetramethoxysilane was added. These were well mixed, and thereafter anaqueous solution prepared by dissolving 2.45 g (0.025 mol) of maleicanhydride in 72 g (4 mols) of distilled water was added while continuingto stir the mixture, and temperature was raised to 60° C. Whilemaintaining the temperature at 60° C., the mixture was heated for 1hour, and thereafter cooled to room temperature, followed by addition of54.5 g (0.25 mol) of trifluoropropyltrimethoxysilane. The mixtureobtained was well mixed, and thereafter a solution prepared bydissolving 42.5 g (0.125 mol) of tetrabutoxytitanium in 230 g (5 mols)of ethyl alcohol was added. While further continuing to stir themixture, the reaction was allowed to proceed for 24 hours to produce amaterial for forming silica-base coated insulation films. With respectto this insulation film forming material, its number average molecularweight was calculated in the same manner as in Example 1. As a result,it was found to be about 2,910. This insulation film forming materialdid not gel at all even after being left to stand at room temperaturefor a month.

Using 1.5 ml of this material for forming silica-base coated insulationfilms, a transparent and uniform silica-base insulation film was formedin the same manner as in Example 1 on a silicon wafer having beenmirror-polished on one side. This insulation film had a layer thicknessof 597 nm. Also, using an optical microscope, the surface of thisinsulation film was observed, and no defects such as cracks or pinholeswere seen.

This silica-base insulation film was subjected to oxygen plasmatreatment in the same manner as in Example 1. As a result, its layerthickness was read to be 573 nm, and it was seen that the layerthickness became smaller by only about 4% even when exposed to oxygenplasma.

Using the optical microscope, the surface of this insulation film wasalso observed, and no defects such as cracks or pinholes were seen. AnIR spectrum of this insulation film was also measured. As a result, anabsorption peak ascribable to the alkyl group (trifluoropropyl group)was also seen after the oxygen plasma treatment; and the film was foundto have a good oxygen plasma resistance.

EXAMPLE 3

In 345 g (7.5 mols) of ethyl alcohol, 152 g (1 mol) oftetramethoxysilane was added. These were well mixed, and thereafter anaqueous solution prepared by dissolving 2.45 g (0.025 mol) of maleicanhydride in 72 g (4 mols) of distilled water was added while continuingto stir the mixture, and temperature was raised to 60° C. Whilemaintaining the temperature at 60° C, the mixture was heated for 1 hour,and thereafter cooled to room temperature, followed by addition of 109 g(0.5 mol) of trifluoropropyltrimethoxysilane. The mixture obtained waswell mixed, and then a solution prepared by dissolving 45.5 g (0.125mol) of titanium dipropoxybisacetylacetonate in 230 g (5 mols) of ethylalcohol was added. While further continuing to stir the mixture, thereaction was allowed to proceed for 24 hours to produce a material forforming silica-base coated insulation films. With respect to thisinsulation film forming material, its number average molecular weightwas calculated in the same manner as in Example 1. As a result, it wasabout 1,650. This insulation film forming material did not gel at alleven after being left to stand at room temperature for a month.

Using 1.5 ml of this material for forming silica-base coated insulationfilms, a transparent and uniform silica-base insulation film was formedin the same manner as in Example 1 on a silicon wafer having beenmirror-polished on one side. This insulation film had a layer thicknessof 749 nm. Also, using an optical microscope, the surface of thisinsulation film was observed, and no defects such as cracks or pinholeswere seen.

This silica-base insulation film was subjected to oxygen plasmatreatment in the same manner as in Example 1. As a result, its layerthickness was read to be 704 nm, and it was seen that the layerthickness became smaller by only about 6% even when exposed to oxygenplasma. Using the optical microscope, the surface of this insulationfilm was also observed, and no defects such as cracks or pinholes wereseen.

An IR spectrum of this insulation film was also measured. As a result,an absorption peak ascribable to the alkyl group (trifluoropropyl group)was seen also after the oxygen plasma treatment, and the film was foundto have a good oxygen plasma resistance.

EXAMPLE 4

In 345 g (7.5 mols) of ethyl alcohol, 152 g (1 mol) oftetramethoxysilane was added. These were well mixed, and thereafter anaqueous solution prepared by dissolving 2.45 g (0.025 mol) of maleicanhydride in 72 g (4 mols) of distilled water was added while continuingto stir the mixture, and temperature was raised to 60° C. Whilemaintaining the temperature at 60° C., the mixture was heated for 1hour, and thereafter cooled to room temperature, followed by addition of109 g (0.5 mol) of trifluoropropyltrimethoxysilane. The mixture obtainedwas well mixed, and then a solution prepared by dissolving 54.4 g (0.125mol) of zirconium dibutoxybisacetylacetonato in 230 g (5 mols) of ethylalcohol was added. While further continuing to stir the mixture, thereaction was allowed to proceed for 24 hours to produce a material forforming silica-base coated insulation films. With respect to thisinsulation film forming material, its number average molecular weightwas calculated in the same manner as in Example 1. As a result, it wasfound to be about 2,300. This insulation film forming material did notgel at all even after being left to stand at room temperature for amonth.

Using 1.5 ml of this material for forming silica-base coated insulationfilms, a transparent and uniform silica-base insulation film was formedin the same manner as in Example 1 on a silicon wafer having beenmirror-polished on one side. This insulation film had a layer thicknessof 654 nm. Also, using an optical microscope, the surface of thisinsulation film was observed, and no defects such as cracks or pinholeswere seen.

This silica-base insulation film was subjected to oxygen plasmatreatment in the same manner as in Example 1. As a result, its layerthickness was read to be 608 nm, and it was seen that the layerthickness became smaller by only about 7% even when exposed to oxygenplasma. Using the optical microscope, the surface of this insulationfilm was also observed, and no defects such as cracks or pinholes wereseen.

An IR spectrum of this insulation film was also measured. As a result,an absorption peak ascribable to the alkyl group (trifluoropropyl group)was also seen after the oxygen plasma treatment, and the film was foundto have a good oxygen plasma resistance.

EXAMPLE 5

In 345 g (7.5 mols) of ethyl alcohol, 152 g (1 mol) oftetramethoxysilane and 136 g (1 mol) of methyltrimethoxysilane wereadded. These were well mixed, and thereafter a solution prepared bydissolving 42.5 g (0.125 mol) of tetrabutoxytitanium in 230 g (5 mols)of ethyl alcohol was added while continuing to stir the mixture. Whilefurther continuing to stir the mixture, the reaction was allowed toproceed for 24 hours to produce a material for forming silica-basecoated insulation films. With respect to this insulation film formingmaterial, its number average molecular weight was calculated in the samemanner as in Example 1. As a result, it was about 3,260. This insulationfilm forming material did not gel at all even after being left to standat room temperature for a month.

Using 1.5 ml of this material for forming silica-base coated insulationfilms, a transparent and uniform silica-base insulation film was formedin the same manner as in Example 1 on a silicon wafer having beenmirror-polished on one side. This insulation film had a layer thicknessof 622 nm. Also, using an optical microscope, the surface of thisinsulation film was observed, and no defects such as cracks or pinholeswere seen.

This silica-base insulation film was subjected to oxygen plasmatreatment in the same manner as in Example 1. As a result, its layerthickness was read to be 585 nm, and it was seen that the layerthickness became smaller by only about 6% even when exposed to oxygenplasma. Using the optical microscope, the surface of this insulationfilm was also observed, and no defects such as cracks or pinholes wereseen.

An IR spectrum of this insulation film was also measured. As a result,an absorption peak ascribable to the alkyl group (methyl group) was alsoseen after the oxygen plasma treatment, and the film was found to have agood oxygen plasma resistance.

EXAMPLE 6

In 345 g (7.5 mols) of ethyl alcohol, 152 g (1 mol) oftetramethoxysilane was added. These were well mixed, and thereafter anaqueous solution prepared by dissolving 2.45 g (0.025 mol) of maleicanhydride in 72 g (4 mols) of distilled water was added while continuingto stir the mixture, and the temperature was raised to 60° C. Whilemaintaining the temperature at 60° C., the mixture was heated for 1hour, and thereafter cooled to room temperature, followed by addition of136 g (1 mol) of methyltrimethoxysilane. The mixture obtained was wellmixed, and then a solution prepared by dissolving 42.5 g (0.125 mol) oftetrabutoxytitanium in 230 g (5 mols) of ethyl alcohol was added. Whilefurther continuing to stir the mixture, the reaction was allowed toproceed for 24 hours to produce a material for forming silica-basecoated insulation films. With respect to this insulation film formingmaterial, its number average molecular weight was calculated in the samemanner as in Example 1. As a result, it was found to be about 3,190.This insulation film forming material did not gel at all even afterbeing left to stand at room temperature for a month.

Using 1.5 ml of this material for forming silica-base coated insulationfilms, a transparent and uniform silica-base insulation film was formedin the same manner as in Example 1 on a silicon wafer having beenmirror-polished on one side. This insulation film had a layer thicknessof 639 nm. Also, using an optical microscope, the surface of thisinsulation film was observed, and no defects such as cracks or pinholeswere seen.

This silica-base insulation film was subjected to oxygen plasmatreatment in the same manner as in Example 1. As a result, its layerthickness was read to be 594 nm, and it was seen that the layerthickness became smaller by only about 7% even when exposed to oxygenplasma. Using the optical microscope, the surface of this insulationfilm was also observed, and no defects such as cracks or pinholes wereseen.

An IR spectrum of this insulation film was also measured. As a result,an absorption peak ascribable to the alkyl group (methyl group) was seenalso after the oxygen plasma treatment, and the film was found to have agood oxygen plasma resistance.

EXAMPLE 7

In 345 g (7.5 mols) of ethyl alcohol, 152 g (1 mol) oftetramethoxysilane was added. These were well mixed, and thereafter anaqueous solution prepared by dissolving 2.45 g (0.025 mol) of maleicanhydride in 72 g (4 mols) of distilled water was added while continuingto stir the mixture, and the temperature was raised to 60° C. Whilemaintaining the temperature at 60° C., the mixture was heated for 1hour, and thereafter cooled to room temperature, followed by addition of136 g (1 mol) of methyltrimethoxysilane. The mixture obtained was wellmixed, and then a solution prepared by dissolving 45.5 g (0.125 mol) oftitanium dipropoxybisacetylacetonate in 230 g (5 mols) of ethyl alcoholwas added. While further continuing to stir the mixture, the reactionwas allowed to proceed for 24 hours to produce a material for formingsilica-base coated insulation films. With respect to this insulationfilm forming material, its number average molecular weight wascalculated in the same manner as in Example 1. As a result, it was foundto be about 1,180. This insulation film forming material did not gel atall even after being left to stand at room temperature for a month.

Using 1.5 ml of this material for forming silica-base coated insulationfilms, a transparent and uniform silica-base insulation film was formedin the same manner as in Example 1 on a silicon wafer having beenmirror-polished on one side. This insulation film had a layer thicknessof 570 nm. Also, using an optical microscope, the surface of thisinsulation film was observed, and no defects such as cracks or pinholeswere seen.

This silica-base insulation film was subjected to oxygen plasmatreatment in the same manner as in Example 1. As a result, its layerthickness was read to be 532 nm, and it was seen that the layerthickness became smaller by only about 7% even when exposed to oxygenplasma. Using the optical microscope, the surface of this insulationfilm was also observed, and no defects such as cracks or pinholes wereseen.

An IR spectrum of this insulation film was also measured. As a result,an absorption peak ascribable to the alkyl group (methyl group) was alsoseen after the oxygen plasma treatment, and the film was found to have agood oxygen plasma resistance.

EXAMPLE 8

In 345 g (7.5 mols) of ethyl alcohol, 152 g (1 mol) oftetramethoxysilane was added. These were well mixed, and thereafter anaqueous solution prepared by dissolving 2.45 g (0.025 mol) of maleicanhydride in 72 g (4 mols) of distilled water was added while continuingto stir the mixture, and temperature was raised to 60° C. Whilemaintaining the temperature at 60° C., the mixture was heated for 1hour, and thereafter cooled to room temperature, followed by addition of136 g (1 mol) of methyltrimethoxysilane. The mixture obtained was wellmixed, and then a solution prepared by dissolving 54.4 g (0.125 mol) ofzirconium dibutoxybisacetylacetonate in 230 g (5 mols) of ethyl alcoholwas added. While further continuing to stir the mixture, the reactionwas allowed to proceed for 24 hours to produce a material for formingsilica-base coated insulation films. With respect to this insulationfilm forming material, its number average molecular weight wascalculated in the same manner as in Example 1. As a result, it was foundto be about 1,390. This insulation film forming material did not gel atall even after being left to stand at room temperature for a month.

Using 1.5 ml of this material for forming silica-base coated insulationfilms, a transparent and uniform silica-base insulation film was formedin the same manner as in Example 1 on a silicon wafer having beenmirror-polished on one side. This insulation film had a layer thicknessof 514 nm. Also, using an optical microscope, the surface of thisinsulation film was observed, and no defects such as cracks or pinholeswere seen.

This silica-base insulation film was subjected to oxygen plasmatreatment in the same manner as in Example 1. As a result, its layerthickness was read to be 478 nm, and it was seen that the layerthickness became smaller by only about 7% even when exposed to oxygenplasma. Using the optical microscope, the surface of this insulationfilm was also observed, and no defects such as cracks or pinholes wereseen.

An IR spectrum of this insulation film was also measured. As a result,an absorption peak ascribable to the alkyl group (methyl group) was alsoseen after the oxygen plasma treatment, and the film was found to have agood oxygen plasma resistance.

EXAMPLE 9

In 575 g (12.5 mols) of ethyl alcohol, 152 g (1 mol) oftetramethoxysilane and 54.5 g (0.25 mol) oftrifluoropropyltrimethoxysilane were added. These were well mixed, andthereafter an aqueous solution prepared by dissolving 3.06 g (0.031 mol)of maleic anhydride in 85.5 g (4.75 mols) of distilled water was addedwhile continuing to stir the mixture. While further continuing to stirthe mixture, the reaction was allowed to proceed for 24 hours to producea material for forming silica-base coated insulation films. With respectto this insulation film forming material, its number average molecularweight was calculated in the same manner as in Example 1. As a result,it was found to be about 1,040. This material did not gel at all evenafter being left to stand at room temperature for a month.

Using 1.5 ml of this material for forming silica-base coated Insulationfilms, a transparent and uniform silica-base insulation film was formedin the same manner as in Example 1 on a silicon wafer having beenmirror-polished on one side. This insulation film had a layer thicknessof 537 nm. Also, using an optical microscope, the surface of thisinsulation film was observed, and no defects such as cracks or pinholeswere seen.

This silica-base insulation film was subjected to oxygen plasmatreatment in the same manner as in Example 1. As a result, its layerthickness was read to be 516 nm, and it was seen that the layerthickness became smaller by only about 4% even when exposed to oxygenplasma. Using the optical microscope, the surface of this insulationfilm was also observed, and no defects such as cracks or pinholes wereseen.

An IR spectrum of this insulation film was also measured. As a result,an absorption peak ascribable to the alkyl group (trifluoropropyl group)was also seen after the oxygen plasma treatment, and the film was foundto have a good oxygen plasma resistance.

EXAMPLE 10

In 575 g (12.5 mols) of ethyl alcohol, 152 g (1 mol) oftetramethoxysilane was added. These were well mixed, and thereafter anaqueous solution prepared by dissolving 2.45 g (0.025 mol) of maleicanhydride in 72 g (4 mols) of distilled water was added while continuingto stir the mixture, and the temperature was raised to 60° C. Whilemaintaining the temperature at 60° C., the mixture was heated for 1hour, and thereafter cooled to room temperature, followed by addition of54.5 g (0.25 mol) of trifluoropropyltrimethoxysilane. The mixtureobtained was well mixed, and then an aqueous solution prepared bydissolving 0.59 g (0.006 mol) of maleic anhydride in 13.5 g (0.75 mol)of distilled water was added. While further continuing to stir themixture, the reaction was allowed to proceed for 24 hours to produce amaterial for forming silica-base coated insulation films. With respectto this insulation film forming material, its number average molecularweight was calculated in the same manner as in Example 1. As a result,it was found to be about 1,880. This insulation film forming materialdid not gel at all even after being left to stand at room temperaturefor a month.

Using 1.5 ml of this material for forming silica-base coated insulationfilms, a transparent and uniform silica-base insulation film was formedin the same manner as in Example 1 on a silicon wafer having beenmirror-polished on one side. This insulation film had a layer thicknessof 538 nm. Also, using an optical microscope, the surface of thisinsulation film was observed, and no defects such as cracks or pinholeswere seen.

This silica-base insulation film was subjected to oxygen plasmatreatment in the same manner as in Example 1. As a result, its layerthickness was read to be 511 nm, and it was seen that the layerthickness became smaller by only about 5% even when exposed to oxygenplasma. Using the optical microscope, the surface of this insulationfilm was also observed, and no defects such as cracks or pinholes wereseen.

An IR spectrum of this insulation film was also measured. As a result,an absorption peak ascribable to the alkyl group (trifluoropropyl group)was also seen after the oxygen plasma treatment, and the film was foundto have a good oxygen plasma resistance.

COMPARATIVE EXAMPLE 1

In 575 g (12.5 mols) of ethyl alcohol, 152 g (1 mol) oftetramethoxysilane and 136 g (1 mol) of methyltrimethoxysilane wereadded. These were well mixed, and thereafter an aqueous solutionprepared by dissolving 4.9 g (0.05 mol) of maleic anhydride in 126 g (7mols) of distilled water was added while continuing to stir the mixture.While further continuing to stir the mixture, the reaction was allowedto proceed for 24 hours to produce a material for forming silica-basecoated insulation films. With respect to this insulation film formingmaterial, its number average molecular weight was calculated in the samemanner as in Example 1. As a result, it was found to be about 780. Thismaterial did not gel at all even after left to stand at room temperaturefor a month.

Using 1.5 ml of this material for forming silica-base coated insulationfilms, a transparent and uniform silica-base insulation film was formedin the same manner as in Example 1 on a silicon wafer having beenmirror-polished on one side. This insulation film had a layer thicknessof 489 nm. Also, using an optical microscope, the surface of thisinsulation film was observed, and no defects such as cracks or pinholeswere seen. This silica-base insulation film was subjected to oxygenplasma treatment in the same manner as in Example 1. As a result, itslayer thickness was read to be 391 nm, and it was seen that the layerthickness became smaller by as much as about 20% when exposed to oxygenplasma. Using the optical microscope, the surface of this insulationfilm was also observed, and a great number of cracks were seen to haveoccurred over the whole surface.

An IR spectrum of this insulation film was also measured. As a result,any absorption peak ascribable to the alkyl group (methyl group) whichhad been seen after the baking at 400° C. was not seen at all after theoxygen plasma treatment, and the alkyl group was found to be releasedbecause of oxygen plasma.

COMPARATIVE EXAMPLE 2

In 575 g (12.5 mols) of ethyl alcohol, 152 g (1 mol) oftetramethoxysilane was added. These were well mixed, and thereafter anaqueous solution prepared by dissolving 2.45 g (0.025 mol) of maleicanhydride in 72 g (4 mols) of distilled water was added while continuingto stir the mixture, and the temperature was raised to 60° C. Whilemaintaining the temperature at 60° C., the mixture was heated for 1hour, and thereafter cooled to room temperature, followed by addition of136 g (1 mol) of methyltrimethoxysilane. The mixture obtained was wellmixed, and then an aqueous solution prepared by dissolving 2.45 g (0.025mol) of maleic anhydride in 54 g (3 mols) of distilled water was added.While further continuing to stir the mixture, the reaction was allowedto proceed for 24 hours to produce a material for forming silica-basecoated insulation films. With respect to this insulation film formingmaterial, its number average molecular weight was calculated in the samemanner as in Example 1. As a result, it was found to be about 980. Thisinsulation film forming material did not gel at all even after beingleft to stand at room temperature for a month.

Using 1.5 ml of this material for forming silica-base coated insulationfilms, a transparent and uniform silica-base insulation film was formedin the same manner as in Example 1 on a silicon wafer having beenmirror-polished on one side. This insulation film had a layer thicknessof 489 nm. Also, using an optical microscope, the surface of thisinsulation film was observed, and no defects such as cracks or pinholeswere seen.

This silica-base insulation film was subjected to oxygen plasmatreatment in the same manner as in Example 1. As a result, its layerthickness was read to be 395 nm, and it was seen that the layerthickness became smaller by as much as about 20% when exposed to oxygenplasma. Using the optical microscope, the surface of this insulationfilm was also observed, and a great number of cracks were seen to haveoccurred over the whole surface.

An IR spectrum of this insulation film was also measured. As a result,any absorption peak ascribable to the alkyl group (methyl group) whichhad been seen after the baking at 400° C. was not seen at all after theoxygen plasma treatment, and the alkyl group was found to be releasedbecause of oxygen plasma.

EXAMPLE 11

In 460.0 g (10 mols) of ethyl alcohol, 136.0 g (1 mol) ofmethyltrimethoxysilane was added. These were well mixed, and thereafteran aqueous solution prepared by dissolving 1.6 g (0.025 mol) of nitricacid in 27.0 g (1.5 mols) of distilled water was added while continuingto stir the mixture, and the reaction was allowed to proceed at roomtemperature for 2 hours as it was. A solution prepared by dissolving170.0 g (0.5 mol) of tetrabutoxytitanium in 460.0 g (10 mols) of ethylalcohol was further added thereto, and the mixture obtained was stirredfor 2 hours. Thereafter, 304.0 g (2 mols) of tetramethoxysilane and460.0 g (10 mols) of ethanol were added thereto. These were well mixed,and thereafter an aqueous solution prepared by dispersing 3.2 g (0.05mol) of nitric acid in 72.0 g (4 mols) of distilled water was added.While continuing to stir the mixture, the reaction was allowed toproceed for 24 hours to produce a material for forming silica-basecoated insulation films. With respect to this insulation film formingmaterial, its molecular weight distribution was measured usingtetrahydrofuran as an eluting solution and using an HPLC (high-speedliquid chromatography) apparatus (Model 6000, manufactured by HitachiLtd.). From the results of measurement, number average molecular weightin terms of polystyrene was calculated (columns used: available fromHitachi Chemical Co., Ltd.; trade name: GELPACK GL-R420; flow rate: 1.75ml/min.). As a result, it was about 2,140. This Insulation film formingmaterial did not gel at all even after being left to stand at roomtemperature for a month.

Using 1.5 ml of this material for forming silica-base coated insulationfilms, a silicon wafer having been mirror-polished on one side wascoated with this material on its surface by means of a spin coater at2,000 rpm for 20 seconds, followed by drying for 30 seconds on a 150° C.hot plate and for 30 seconds on a 250° C. hot plate to remove thesolvent. Subsequently, using a tubular baking furnace and in anatmosphere of nitrogen, the coating formed was heated at 430° C. for 30minutes to cure, to thereby obtain a transparent and uniform silica-baseinsulation film. Using an optical interference layer thickness meter(trade name: LAMBDA ACE; manufactured by Dainippon Screen Mfg. Co.,Ltd.), the thickness of this insulation film was measured, and it wasfound to be 279 nm. Also, using an optical microscope, the surface ofthis insulation film was observed, and no defects such as cracks orpinholes were seen.

This silica-base insulation film was subjected to oxygen plasmatreatment using a barrel type isotropic plasma etching apparatus andunder conditions of oxygen:1 Torr, output: 400 W, time: 20 minutes.Thereafter, the thickness of the film thus treated was measured toreveal that it was 272 nm, and it was seen that its layer thicknessbecame smaller by only about 2% even when exposed to oxygen plasma.Also, using the optical microscope, the surface of this insulation filmwas observed, and no defects such as cracks or pinholes were seen. An IRspectrum of this insulation film was also measured. As a result, anabsorption peak ascribable to the alkyl group (methyl group) was alsoseen after the oxygen plasma treatment, and the film was found to have agood oxygen plasma resistance.

EXAMPLE 12

In 460.0 g (10 mols) of ethyl alcohol, 136.0 g (1 mol) ofmethyltrimethoxysilane was added. These were well mixed, and thereafteran aqueous solution prepared by dissolving 1.6 g (0.025 mol) of nitricacid in 27.0 g (1.5 mols) of distilled water was added while continuingto stir the mixture, and the reaction was allowed to proceed at roomtemperature for 2 hours as it was. A solution prepared by dissolving182.0 g (0.5 mol) of titanium dipropoxybisacetylacetonate in 460.0 g (10mols) of ethyl alcohol was further added thereto, and the mixtureobtained was stirred for 2 hours. Thereafter, 304.0 g (2 mols) oftetramethoxysilane and 460.0 g (10 mols) of ethanol were added thereto.These were well mixed, and then an aqueous solution prepared bydissolving 3.2 g (0.05 mol) of nitric acid in 72.0 g (4 mols) ofdistilled water was added. While continuing to stir the mixture, thereaction was allowed to proceed for 24 hours to produce a material forforming silica-base coated insulation films. The number averagemolecular weight of this insulation film forming material was calculatedin the same manner as in Example 11. As a result, it was found to beabout 1,430. This insulation film forming material did not gel at alleven after being left to stand at room temperature for a month.

Using 1.5 ml of this material for forming silica-base coated insulationfilms, a transparent and uniform silica-base insulation film was formedin the same manner as in Example 11 on a silicon wafer having beenmirror-polished on one side. This insulation film had a layer thicknessof 246 nm. Also, using an optical microscope, the surface of thisinsulation film was observed, and no defects such as cracks or pinholeswere seen.

This silica-base insulation film was subjected to oxygen plasmatreatment in the same manner as in Example 11. As a result, its layerthickness was read and found to be 234 nm, and it was seen that thelayer thickness became smaller by only about 5% even when exposed tooxygen plasma. Using the optical microscope, the surface of thisinsulation film was also observed, and no defects such as cracks orpinholes were seen.

An IR spectrum of this insulation film was also measured. As a result,an absorption peak ascribable to the alkyl group (methyl group) was alsoseen after the oxygen plasma treatment, and the film was found to have agood oxygen plasma resistance.

EXAMPLE 13

In 460.0 g (10 mols) of ethyl alcohol, 216.0 g (1 mol) oftrifluoropropyltrimethoxysilane was added. These were well mixed, andthereafter an aqueous solution prepared by dissolving 1.6 g (0.025 mol)of nitric acid in 27.0 g (1.5 mols) of distilled water was added whilecontinuing to stir the mixture, and the reaction was allowed to proceedat room temperature for 2 hours as it was. A solution prepared bydissolving 170.0 g (0.5 mol) of tetrabutoxytitanium in 460.0 g (10 mols)of ethyl alcohol was further added thereto, and the mixture obtained wasstirred for 2 hours. Thereafter, 304.0 g (2 mols) of tetramethoxysilaneand 460.0 g (10 mols) of ethanol were added thereto. These were wellmixed, and then an aqueous solution prepared by dissolving 3.2 g (0.05mol) of nitric acid in 72.0 g (4 mols) of distilled water was added.While continuing to stir the mixture, the reaction was allowed toproceed for 24 hours to produce a material for forming silica-basecoated insulation films. The number average molecular weight of thisinsulation film forming material was calculated in the same manner as inExample 11. As a result, it was found to be about 1,520. This insulationfilm forming material did not gel at all even after being left to standat room temperature for a month.

Using 1.5 ml of this material for forming silica-base coated insulationfilms, a transparent and uniform silica-base insulation film was formedin the same manner as in Example 11 on a silicon wafer having beenmirror-polished on one side. This insulation film had a layer thicknessof 259 nm. Also, using an optical microscope, the surface of thisinsulation film was observed, and no such as cracks or pinholes wereseen.

This silica-base insulation film was subjected to oxygen plasmatreatment in the same manner as in Example 11. As a result, its layerthickness was read was found to be 246 nm, and it was seen that thelayer thickness became smaller by only about 5% even when exposed tooxygen plasma. Using the optical microscope, the surface of thisinsulation film was also observed, and no defects such as cracks orpinholes were seen.

An IR spectrum of this insulation film was also measured. As a result,an absorption peak ascribable to the alkyl group (trifluoropropyl group)was also seen after the oxygen plasma treatment, and the film was foundto have a good oxygen plasma resistance.

COMPARATIVE EXAMPLE 3

In 920.0 g (20 mols) of ethyl alcohol, 136.0 g (1 mol) ofmethyltrimethoxysilane was added. These were well mixed, and thereafteran aqueous solution prepared by dissolving 1.6 g (0.025 mol) of nitricacid in 27.0 g (1.5 mols) of distilled water was added while continuingto stir the mixture, and the reaction was allowed to proceed at roomtemperature for 2 hours as it was. Then, 304.0 g (2 mols) oftetramethoxysilane and 460.0 g (10 mols) of ethanol were added thereto.These were well mixed, and then an aqueous solution prepared bydissolving 3.2 g (0.05 mol) of nitric acid in 72.0 g (4 mols) ofdistilled water was added. While continuing to stir the mixture, thereaction was allowed to proceed for 24 hours to produce a material forforming silica-base coated insulation films. The number averagemolecular weight of this insulation film forming material was calculatedin the same manner as in Example 11. As a result, it was found to beabout 780. This insulation film forming material did not gel at all evenafter being left to stand at room temperature for a month.

Using 1.5 ml of this material for forming silica-base coated insulationfilms, a transparent and uniform silica-base insulation film was formedin the same manner as in Example 11 on a silicon wafer having beenmirror-polished on one side. This insulation film had a layer thicknessof 259 nm. Also, using an optical microscope, the surface of thisinsulation film was observed, and no defects such as cracks or pinholeswere seen.

This silica-base insulation film was subjected to oxygen plasmatreatment in the same manner as in Example 11. As a result, its layerthickness was read and found to be 195 nm, and it was seen that thelayer thickness became smaller by as much as about 24% when exposed tooxygen plasma. Using the optical microscope, the surface of thisinsulation film was also observed, and a great number of cracks wereseen to have occurred over the whole surface.

An IR spectrum of this insulation film was also measured. As a result,no absorption peak ascribable to the alkyl group (methyl group) whichhad been seen after the baking at 430° C. was seen at all after theoxygen plasma treatment, and the alkyl group was found to be releasedbecause of oxygen plasma.

EXAMPLE 14

In 920.0 g (20 mols) of ethyl alcohol, 408.0 g (3 mols) ofmethyltrimethoxysilane was added. These were well mixed, and thereafteran aqueous solution prepared by dispersing 4.7 g (0.075 mol) of nitricacid in 81.0 g (4.5 mols) of distilled water was added while continuingto stir the mixture, and the reaction was allowed to proceed at roomtemperature for 2 hours as it was. A solution prepared by dissolving170.0 g (0.5 mol) of tetrabutoxytitanium in 460.0 g (10 mols) of ethylalcohol was further added thereto. While continuing to stir the mixture,the reaction was allowed to proceed for 24 hours to produce a materialfor forming silica-base coated Insulation films. With respect to thisinsulation film forming material, its molecular weight distribution wasmeasured using tetrahydrofuran as an eluting solution and using an HPLC(high-speed liquid chromatography) apparatus (Model 6000, manufacturedby Hitachi Ltd.). From the results of measurement, number averagemolecular weight in terms of polystyrene was calculated (columns used:available from Hitachi Chemical Co., Ltd.; trade name: GELPACK GL-R420;flow rate: 1.75 ml/min.). As a result, it was found to be about 1,550.This insulation film forming material did not gel at all even afterbeing left to stand at room temperature for a month.

Using 1.5 ml of this material for forming silica-base coated insulationfilms, a silicon wafer having been mirror-polished on one side wascoated with this material on Its surface by means of a spin coater at2,000 rpm for 20 seconds, followed by drying for 30 seconds on a 150° C.hot plate and for 30 seconds on a 250° C. hot plate to remove thesolvent. Subsequently, using a tubular baking furnace and in anatmosphere of nitrogen, the coating for ed was heated at 430° C. for 30minutes to cure, to thereby obtain a transparent and uniform silica-baseinsulation film. Using an optical interference layer thickness meter(trade name: LAMBDA ACE; manufactured by Dainippon Screen Mfg. Co.,Ltd.), the thickness of this insulation film was measured, and it wasfound to be 305 nm. Also, using an optical microscope, the surface ofthis insulation film was observed, and no defects such as cracks orpinholes were seen.

This silica-base insulation film was subjected to oxygen plasmatreatment using a barrel type isotropic plasma etching apparatus andunder conditions of oxygen: 1 Torr, output: 400 W, time: 20 minutes.Thereafter, the thickness of the film thus treated was measured toreveal that it was 292 nm, and it was seen that its layer thicknessbecame smaller by only about 4% even when exposed to oxygen plasma.Also, using an optical microscope, the surface of this insulation filmwas observed, where no defects such as cracks or pinholes were seen.

An IR spectrum of this insulation film was also measured. As a result,an absorption peak ascribable to the alkyl group (methyl group) was seenalso after the oxygen plasma treatment, and the film was found to have agood oxygen plasma resistance.

EXAMPLE 15

In 920.0 g (20 mols) of ethyl alcohol, 408.0 g (3 mols) ofmethyltrimethoxysilane was added. These were well mixed, and thereafteran aqueous solution prepared by dissolving 4.7 g (0.075 mol) of nitricacid in 81.0 g (4.5 mols) of distilled water was added while continuingto stir the mixture, and the reaction was allowed to proceed at roomtemperature for 2 hours as it was. A solution prepared by dissolving182.0 g (0.5 mol) of titanium dipropoxybisacetylacetonate in 460.0 g (10mols) of ethyl alcohol was further added thereto. While continuing tostir the mixture, the reaction was allowed to proceed for 24 hours toproduce a material for forming silica-base coated insulation films. Thenumber average molecular weight of this insulation film forming materialwas calculated in the same manner as in Example 14. As a result, it wasabout 1,520. This insulation film forming material did not gel at alleven after being left to stand at room temperature for a month.

Using 1.5 ml of this material for forming silica-base coated insulationfilms, a transparent and uniform silica-base insulation film was formedin the same manner as in Example 14 on a silicon wafer having beenmirror-polished on one side. This insulation film had a layer thicknessof 292 nm. Also, using an optical microscope, the surface of thisinsulation film was observed, and no defects such as cracks or pinholeswere seen.

This silica-base insulation film was subjected to oxygen plasmatreatment in the same manner as in Example 14. As a result, its layerthickness was read and found to be 281 nm, and it was seen that thelayer thickness became smaller by only about 4% even when exposed tooxygen plasma. Using the optical microscope, the surface of thisinsulation film was also observed, and no defects such as cracks orpinholes were seen.

An IR spectrum of this insulation film was also measured. As a result,an absorption peak ascribable to the alkyl group (methyl group) was alsoseen after the oxygen plasma treatment, and the film was found to have agood oxygen plasma resistance.

EXAMPLE 16

In 920.0 g (20 mols) of ethyl alcohol, 648.0 g (3 mol) oftrifluoropropyltrimethoxysilane was added. These were well mixed, andthereafter an aqueous solution prepared by dissolving 4.7 g (0.075 mol)of nitric acid in 81.0 g (4.5 mols) of distilled water was added whilecontinuing to stir the mixture, and the reaction was allowed to proceedat room temperature for 2 hours as it was. A solution prepared bydissolving 170.0 g (0.5 mol) of tetrabutoxytitanium in 460.0 g (10 mols)of ethyl alcohol was further added thereto. While continuing to stir themixture, the reaction was allowed to proceed for 24 hours to produce amaterial for forming silica-base coated insulation films. The numberaverage molecular weight of this insulation film forming material wascalculated in the same manner as in Example 14. As a result, it wasfound to be about 1,230. This insulation film forming material did notgel at all even after left to stand at room temperature for a month.

Using 1.5 ml of this material for forming silica-base coated insulationfilms, a transparent and uniform silica-base insulation film was formedin the same manner as in Example 14 on a silicon wafer having beenmirror-polished on one side. This insulation film had a layer thicknessof 303 nm. Also, using an optical microscope, the surface of thisinsulation film was observed, and no defects such as cracks or pinholeswere seen.

This silica-base insulation film was subjected to oxygen plasmatreatment in the same manner as in Example 14. As a result, its layerthickness was read to be 292 nm, and it was seen that the layerthickness became smaller by only about 4% even when exposed to oxygenplasma. Using the optical microscope, the surface of this insulationfilm was also observed, and no defects such as cracks or pinholes wereseen.

An IR spectrum of this insulation film was also measured. As a result,an absorption peak ascribable to the alkyl group (trifluoropropyl group)was also seen after the oxygen plasma treatment, and the film was foundto have a good oxygen plasma resistance.

COMPARATIVE EXAMPLE 4

In 920.0 g (20 mols) of ethyl alcohol, 136.0 g (1 mol) ofmethyltrimethoxysilane was added. These were well mixed, and thereafteran aqueous solution prepared by dissolving 1.6 g (0.025 mol) of nitricacid in 27.0 g (1.5 mols) of distilled water was added while continuingto stir the mixture, and the reaction was. allowed to proceed at roomtemperature for 24 hours as it was, to produce a material for formingsilica-base coated insulation films. With respect to this insulationfilm forming material, the number average molecular weight wascalculated in the same manner as in Example 14. As a result, it wasfound to be about 880. This insulation film forming material did not gelat all even after being left to stand at room temperature for a month.

Using 1.5 ml of this material for forming silica-base coated insulationfilms, a transparent and uniform silica-base insulation film was formedin the same manner as in Example 14 on a silicon wafer having beenmirror-polished on one side. This insulation film had a layer thicknessof 206 nm. Also, using an optical microscope, the surface of thisinsulation film was observed, and no defects such as cracks or pinholeswere seen.

This silica-base insulation film was subjected to oxygen plasmatreatment in the same manner as in Example 14. As a result, its layerthickness was read and found to be 129 nm, and it was seen that thelayer thickness became smaller by as much as about 37% when exposed tooxygen plasma. Using the optical microscope, the surface of thisinsulation film was also observed, and a great number of cracks wereseen to have occurred over the whole surface.

An IR spectrum of this insulation film was also measured. As a result,any absorption peak ascribable to the alkyl group (methyl group) whichhad been seen after the baking at 430° C. was not seen at all after theoxygen plasma treatment, and the alkyl group was found to be releasedbecause of oxygen plasma.

EXAMPLE 17

In 345 g (7.5 mols) of ethyl alcohol, 152 g (1 mol) oftetramethoxysilane and 136 g (1 mol) of methyltrimethoxysilane wereadded. These were well mixed, and thereafter a solution prepared bydissolving 42.5 g (0.125 mol) of tetrabutoxytitanium in 230 g (5 mols)of ethyl alcohol was added while continuing to stir the mixture. Whilefurther continuing to stir the mixture, the reaction was allowed toproceed for 24 hours, and thereafter, 16.5 g (0.04 mol) oftriphenylsulfonium trifluoromethanesulfonate was added and completelydissolved to produce a material for forming silica-base coated thinfilms. With respect to this insulation film forming material, itsmolecular weight distribution was measured using tetrahydrofuran as aneluting solution and using an HPLC (high-speed liquid chromatography)apparatus (Model 6000, manufactured by Hitachi Ltd.). From the resultsof measurement, number average molecular weight in terms of polystyrenewas calculated (columns used: available from Hitachi Chemical Co., Ltd.;trade name: GELPACK GL-R420; flow rate: 1.75 ml/min.). As a result, itwas found to be about 3,260. This thin-film forming material did not gelat all even after being left to stand at room temperature for a month.

Using 1.5 ml of this material for forming silica-base coated thin films,a silicon wafer having been mirror-polished on one side was coated withthis material on its surface by means of a spin coater at 3,000 rpm for30 seconds, followed by drying for 1 minute on an 80° C. hot plate toremove the solvent. On this silicon wafer, a metal mask (a stainlesssteel sheet from which a stripe pattern was punched) was placed andirradiated by light (maximum wavelength: 254 nm) of a low-pressuremercury lamp for 10 minutes, followed by heat-curing on a 120° C. hotplate for 2 minutes. The cured product obtained was developed in amethyl isobutyl ketone solution for 2 minutes, followed by washing withcyclohexane, whereby a silica-base thin film having a patterncorresponding to the metal mask pattern was formed on the silicon wafer.Using an optical microscope, the surface of this thin film was observed,and no defects such as cracks or pinholes were seen.

EXAMPLE 18

In 345 g (7.5 mols) of ethyl alcohol, 152 g (1 mol) oftetramethoxysilane was added. These were well mixed, and thereafter anaqueous solution prepared by dissolving 2.45 g (0.025 mol) of maleicanhydride in 72 g (4 mols) of distilled water was added while continuingto stir the mixture, and temperature was raised to 60° C. Whilemaintaining the temperature at 60° C., the mixture was heated for 1hour, and thereafter cooled to room temperature, followed by addition of136 g (1 mol) of methyltrimethoxysilane. The mixture obtained was wellmixed, and then a solution prepared by dissolving 42.5 g (0.125 mol) oftetrabutoxytitanium in 230 g (5 mols) of ethyl alcohol was added. Whilefurther continuing to stir the mixture, the reaction was allowed toproceed for 24 hours, and thereafter 16.5 g (0.04 mol) oftriphenylsulfonium trifluoromethanesulfonate was added and completelydissolved to produce a material for forming silica-base coated thinfilms. With respect to this thin film forming material, its numberaverage molecular weight was calculated in the same manner as in Example17. As a result, it was found to be about 3,190. This thin-film formingmaterial did not gel at all even after being left to stand at roomtemperature for a month.

Using 1.5 ml of this material for forming silica-base coated thin films,a patterned silica-base thin film was obtained in the same manner as inExample 17 on a silicon wafer having been mirror-polished on one side.Using an optical microscope, the surface of this thin film was observed,and no defects such as cracks or pinholes were seen.

EXAMPLE 19

In 345 g (7.5 mols) of ethyl alcohol, 152 g (1 mol) oftetramethoxysilane was added. These were well mixed, and thereafter anaqueous solution prepared by dissolving 2.45 g (0.025 mol) of maleicanhydride in 72 g (4 mols) of distilled water was added while continuingto stir the mixture, and the temperature was raised to 60° C. Whilemaintaining the temperature at 60° C., the mixture was heated for 1hour, and thereafter cooled to room temperature, followed by addition of136 g (1 mol) of methyltrimethoxysilane. The mixture obtained was wellmixed, and then a solution prepared by dissolving 45.5 g (0.125 mol) oftitanium dipropoxybisacetylacetonate in 230 g (5 mols) of ethyl alcoholwas added. While further continuing to stir the mixture, the reactionwas allowed to proceed for 24 hours, and thereafter 16.5 g (0.04 mol) oftriphenylsulfonium trifluoromethanesulfonate was added and completelydissolved to produce a material for forming silica-base coated thinfilms. With respect to this thin film forming material, its numberaverage molecular weight was calculated in the same manner as in Example17. As a result, it was found to be about 1,180. This thin-film formingmaterial did not gel at all even after being left to stand at roomtemperature for a month.

Using 1.5 ml of this material for forming silica-base coated thin films,a patterned silica-base thin film was obtained in the same manner as inExample 17 on a silicon wafer having been mirror-polished on one side.Using an optical microscope, the surface of this thin film was observed,and no defects such as cracks or pinholes were seen. FIG. 3 shows theresults of measurement on surface roughness of this silica-base thinfilm, measured by means of a contact type surface profile analyzer. Asis seen from these results, the silica-base thin film obtained had alayer thickness of about 400 nm and a pattern corresponding to the metalmask pattern was formed on the surface.

EXAMPLE 20

In 345 g (7.5 mols) of ethyl alcohol, 152 g (1 mol) oftetramethoxysilane was added. These were well mixed, and thereafter anaqueous solution prepared by dissolving 2.45 g (0.025 mol) of maleicanhydride in 72 g (4 mols) of distilled water was added while continuingto stir the mixture, and the temperature was raised to 60° C. Whilemaintaining the temperature at 60° C., the mixture was heated for 1hour, and thereafter cooled to room temperature, followed by addition of109 g (0.5 mol) of trifluoropropyltrimethoxysilane. The mixture obtainedwas well mixed, and then a solution prepared by dissolving 54.5 g (0.125mol) of titanium dipropoxybisacetylacetonate in 230 g (5 mols) of ethylalcohol was added. While further continuing to stir the mixture, thereaction was allowed to proceed for 24 hours, and thereafter 16.5 g(0.04 mol) of triphenylsulfonium trifluoromethanesulfonate was added andcompletely dissolved to produce a material for forming silica-basecoated thin films. With respect to this thin film forming material, itsnumber average molecular weight was calculated in the same manner as inExample 17. As a result, it was found to be about 1,650. This thin-filmforming material did not gel at all even after being left to stand atroom temperature for a month.

Using 1.5 ml of this material for forming silica-base coated thin films,a patterned silica-base thin film was obtained in the same manner as inExample 17 on a silicon wafer having been mirror-polished on one side.Using an optical microscope, the surface of this thin film was observed,and no defects such as cracks or pinholes were seen.

COMPARATIVE EXAMPLE 5

In 575 g (12.5 mols) of ethyl alcohol, 152 g (1 mol) oftetramethoxysilane and 136 g (1 mol) of methyltrimethoxysilane wereadded. These were well mixed, and thereafter an aqueous solutionprepared by dissolving 4.9 g (0.05 mol) of maleic anhydride in 126 g (7mols) of distilled water was added while continuing to stir the mixture.While further continuing to stir the mixture, the reaction was allowedto proceed for 24 hours to produce a material for forming silica-basecoated thin films. With respect to this insulation film formingmaterial, its number average molecular weight was calculated in the samemanner as in Example 17. As a result, it was found to be about 780. Thisthin-film forming material, being left to stand at room temperature,caused a gradual increase in molecular weight, and a precipitate beganto occur in about a month.

Using 1.5 ml of this material for forming silica-base coated thin films,a silica-base thin film was formed in the same manner as in Example 17on a silicon wafer having been mirror-polished on one side. Using anoptical microscope, the surface of this thin film was observed, and nosuch as cracks or pinholes were seen, but no pattern corresponding tothe metal mask pattern was not seen at all. From the results ofmeasurement on surface roughness by means of the surface profileanalyzer, no hills or valleys corresponding to the metal mask patternwere seen at all.

The materials for forming silica-base coated insulation films accordingto the first to fifth invention of the present application have storagestability and also enable thick-layer formation with ease by spincoating etc. Silica-base insulation films produced using this materialfor forming silica-base coated insulation films are transparent anduniform films and are those in which no defects such as cracks orpinholes are seen. Moreover, when this insulation film is subjected tooxygen plasma treatment, its layer thickness does not become muchsmaller, and not only do no defects such as cracks or pinholes occur onits surface but also not so much change is seen in the constituents offilms. Thus, a superior oxygen plasma resistance is seen.

The material for forming silica-base coated thin films according to thesixth invention of the present application has a storage stability andalso enables thick-layer formation with ease by spin coating etc.Silica-base thin films produced using this material for formingsilica-base coated thin films are transparent and uniform films and arethose in which none of defects such as cracks or pinholes are seen.Moreover, when thin films are produced, they can be formed into apattern by exposure to light.

I claim:
 1. A process for producing the material for forming asilica-base coated insulation film comprising(a) an alkoxysilane, apartially hydrolyzed alkoxysilane or mixtures thereof; (b) afluorine-containing alkoxysilane; (c) at least one of an alkoxide of Ti,an alkoxide of Zr and derivatives thereof; and (d) an organicsolvent,wherein a total amount of said component (a) and said component(b) is 1-40 parts by weight based on 100 parts by weight of said organicsolvent (d), and said process comprising mixing an alkoxysilane and afluorine-containing alkoxysilane in an organic solvent, followed byaddition of at least one of an alkoxide of Ti, an alkoxide of Zr andderivatives thereof.
 2. A process for producing the material for forminga silica-base coated insulation film comprising(a) an alkoxysilane, apartially hydrolyzed alkoxysilane or mixtures thereof; (b) afluorine-containing alkoxysilane; (c) at least one of an alkoxide of Ti,an alkoxide of Zr and derivatives thereof; and (d) an organicsolvent,wherein a total amount of said component (a) and said component(b) is 1-40 parts by weight based on 100 parts by weight of said organicsolvent (d), and said process comprising synthesizing a partiallyhydrolyzed product of an alkoxysilane in an organic solvent, and mixinga fluorine-containing alkoxysilane in the product, followed by additionof at least one of an alkoxide of Ti, an alkoxide of Zr and derivativesthereof.
 3. A process for producing the material for forming asilica-base coated insulation film comprising:(a) an alkoxysilane, apartially hydrolyzed alkoxysilane or mixtures thereof; (b) analkylalkoxysilane; (c) at least one of an alkoxide of Ti, an alkoxide ofZr and derivatives thereof; and (d) an organic solvent,wherein a totalamount of said component (a) and said component (b) is 1-40 parts byweight based on 100 parts by weight of said organic solvent (d), andsaid process comprising mixing an alkoxysilane and an alkylalkoxysilanein an organic solvent, followed by addition of at least one of analkoxide of Ti, an alkoxide of Zr and derivatives thereof.
 4. A processfor producing the material for forming a silica-base coated insulationfilm comprising:(a) an alkoxysilane, a partially hydrolyzed alkoxysilaneor mixtures thereof; (b) an alkylalkoxysilane; (c) at least one of analkoxide of Ti, an alkoxide of Zr and derivatives thereof; and (d) anorganic solvent,wherein a total amount of said component (a) and saidcomponent (b) is 1-40 parts by weight based on 100 parts by weight ofsaid organic solvent (d), and said process comprising synthesizing apartially hydrolyzed product of an alkoxysilane in an organic solvent,and mixing an alkylalkoxysilane in the product, followed by addition ofat least one of an alkoxide of Ti, an alkoxide of Zr and derivativesthereof.
 5. A process for producing a material for forming a silica-basecoated insulation film comprising:(a) an alkoxysilane; (b) analkylalkoxysilane, a fluorine-containing alkoxysilane, or mixturesthereof; (c) at least one of an alkoxide of Ti, an alkoxide of Zr andderivatives thereof; (d) an organic solvent; and (e) water and acatalyst;said process comprising mixing the alkylalkoxysilane, thefluorine-containing alkoxysilane or mixtures thereof, the water, and thecatalyst in an organic solvent, thereafter adding at least one of thealkoxide of Ti, the alkoxide of Zr and derivatives thereof, thealkoxysilane, and thereafter adding the water and the catalyst.
 6. Aprocess for producing the material for forming a silica-base coatedinsulation film comprising:(a) an alkylalkoxysilane, afluorine-containing alkoxysilane or mixtures thereof; (b) at least oneof an alkoxide of Ti, an alkoxide of Zr and derivatives thereof; (c) anorganic solvent; and (d) water and a catalyst,wherein a total amount ofsaid alkylalkoxysilane and said fluorine-containing alkoxysilane is 1-40parts by weight based on 100 parts by weight of said organic solvent,and said process comprising mixing an alkylalkoxysilane, afluorine-containing alkoxysilane, or mixtures thereof and water and acatalyst in an organic solvent, followed by addition of at least one ofan alkoxide of Ti, an alkoxide of Zr and derivatives thereof.
 7. Aprocess for producing the material for forming a silica-base coatedinsulation film comprising:(a) an alkoxysilane, a partially hydrolyzedalkoxysilane, or mixtures thereof; (b) an alkylalkoxysilane, afluorine-containing alkoxysilane or mixtures thereof; (c) at least oneof an alkoxide of Ti, an alkoxide of Zr and derivatives thereof; (d) anorganic solvent; and (g) a photo-acid generator,wherein a total amountof said alkoxysilane and said alkylalkoxysilane and/or saidfluorine-containing alkoxysilane is 1-40 parts by weight based on 100parts by weight of said organic solvent, and said process comprisingmixing an alkoxysilane and an alkylalkoxysilane, a fluorine-containingalkoxysilane or mixtures thereof, followed by addition of at least oneof an alkoxide of Ti, an alkoxide of Zr and derivatives thereof, andfurther followed by addition of a photo-acid-generator.
 8. A process forproducing the material for forming a silica-base coated insulating filmcomprising:(a) an alkoxysilane, a partially hydrolyzed alkoxysilane, ormixtures thereof; (b) an alkylalkoxysilane, a fluorine-containingalkoxysilane or mixtures thereof; (c) at least one of an alkoxide of Ti,an alkoxide of Zr and derivatives thereof; (d) an organic solvent; and(g) a photo-acid generator,wherein a total amount of said alkoxysilaneand said alkylalkoxysilane and/or said fluorine-containing alkoxysilaneis 1-40 parts by weight based on 100 parts by weight of said organicsolvent, and said process comprising synthesizing a partially hydrolyzedproduct of an alkoxysilane in an organic solvent, and mixing analkylalkoxysilane, a fluorine-containing alkoxysilane or mixturesthereof in the product, followed by addition of at least one of analkoxide of Ti, an alkoxide of Zr and derivatives thereof, and furtherfollowed by addition of a photo-acid-generator.